Colored coating composition

Abstract

PCT No. PCT/JP95/02687 Sec. 371 Date Jul. 11, 1997 Sec. 102(e) Date Jul. 11, 1997 PCT Filed Dec. 26, 1995 PCT Pub. No. WO96/21703 PCT Pub. Date Jul. 18, 1996A colored coating composition comprising (a) 5 to 60% by weight of a polymer having a carboxyl group and a carboxylate group; (b) 5 to 60% by weight of a polymer having a hydroxyl group and an epoxy group; (c) 0.05 to 20% by weight of a pigment-dispersing agent; and (d) 0.1 to 50% by weight of a pigment; (wherein, each amount formulated of the components (a) to (d) is based on the weight of total solid in the colored coating composition), wherein, an acid total amount AR and a base total amount BR which are derived from said pigment-dispersing agent, and an acid total amount AP and a base total amount BP which are derived from said pigment, suffice the following relations: AR>0.5 BP or BR>0.5 AP, and AR+AP >BR. Thus provided is a solid color coating composition that can meet the requirements of mar resistance, acid resistance, storage stability, and excellent appearance.

We claim: 
     
       1. A colored coating composition comprising (a) 5 to 60% by weight of a polymer having a carboxyl group and a carboxylate group, which is obtained by reacting: (i) an acid anhydride group-containing polymer, obtained by copolymerizing (1) 15 to 40% by weight of an acid anhydride group-containing ethylenically unsaturated monomer, with   (2) 60 to 85% by weight of the other copolymerizable ethylenically unsaturated monomer; with     (ii) a hydroxyl group-containing compound having 1 to 12 carbon atoms; in an amount so that a molar ratio of the acid anhydride group to the hydroxyl group becomes 1/10 to 1/1;       (b) 5 to 60% by weight of a polymer having a hydroxyl group and an epoxy group, which is obtained by copolymerizing: (i) 5 to 70% by weight of a hydroxyl group-containing ethylenically unsaturated monomer represented by the formula: ##STR10## (wherein R is a hydrogen atom or a methyl group, and X is an organic chain represented by the formula: ##STR11## (wherein Y is a linear or branched alkylene group having 2 to 8 carbon atoms, m is an integer of 3 to 7 and q is an integer of 0 to 4) or     an organic chain represented by the formula: ##STR12##  (wherein R is a hydrogen atom or a methyl group and n is an integer of 2 to 50)) and (ii) 10 to 60% by weight of an epoxy group-containing ethylenically unsaturated monomer, and optionally   (iii) 0 to 85% by weight of the other copolymerizable ethylenically unsaturated monomer;     (c) 0.05 to 20% by weight of a pigment-dispersing agent; and   (d) 0.1 to 50% by weight of a pigment; (wherein, each amount formulated of the components (a) to (d) is based on the weight of total solid in the colored coating composition),   wherein, an acid total amount AR and a base total amount BR which are derived from said pigment-dispersing agent, and an acid total amount AP and a base total amount BP which are derived from said pigment, suffice the following relations:     AR>0.5 BP or BR>0.5 AP,     and     AR+AP>BR.       
     
     
       2. The colored coating composition according to claim 1, wherein said polymer (a) having a carboxyl group and a carboxylate group has a number average molecular weight of 1500 to 8000 and an acid value of 5 to 300 mgKOH/g based on solid. 
     
     
       3. The colored coating composition according to claim 1, wherein said acid anhydride group-containing ethylenically unsaturated monomer (a)(i)(1) is selected from the group consisting of itaconic anhydride, maleic anhydride, citraconic anhydride and a mixture thereof. 
     
     
       4. The colored coating composition according to claim 1, wherein said hydroxyl group-containing compound (a)(ii) is monoalcohol. 
     
     
       5. The colored coating composition according to claim 4, wherein said monoalcohol is selected from the group consisting of acetol, allyl alcohol, propargyl alcohol, furfuryl alcohol and methanol. 
     
     
       6. The colored coating composition according to claim 1, wherein said polymer (b) having a hydroxyl group and an epoxy group carries 2 to 10 epoxy groups in the molecule, and has an epoxy equivalent of 100 to 800, a hydroxyl equivalent of 200 to 1200 and a number average molecular weight of 500 to 8000. 
     
     
       7. The colored coating composition according to claim 1, wherein said pigment-dispersing agent is a polyurethane-based, polyurea-based, polyester-based or acryl-based resin. 
     
     
       8. The colored coating composition according to claim 1, wherein said pigment is an inorganic pigment. 
     
     
       9. The colored coating composition according to claim 8, wherein said pigment is selected from the group consisting of titanium oxide, iron oxide and carbon black. 
     
     
       10. The colored coating composition according to claim 1 further comprising a polyester having an acid value of 5 to 300 mgKOH/g (solid), a hydroxyl value of 5 to 300 mgKOH/g (solid) and a number average molecular weight of 400 to 6000 in an amount of up to 60% by weight based on the weight of total solid in the colored coating composition. 
     
     
       11. The colored coating composition according to claim 1 further comprising an aminoplast in an amount of up to 40% by weight based on the weight of total solid in the colored coating composition. 
     
     
       12. The colored coating composition according to claim 11, wherein said aminoplast is a melamine modified compound. 
     
     
       13. The colored coating composition according to claim 1 further comprising a silicone polymer having an epoxy group and an alkoxy group and having an epoxy equivalent of 100 to 1500 and an alkoxy equivalent of 50 to 1500, which is represented by the formula: ##STR13## (wherein R 1  to R 6  independently represents a substituent selected from the group consisting of an alkyl group having 1 to 10 carbon atoms, a phenyl group having 1 to 10 carbon atoms, a phenethyl group having 1 to 10 carbon atoms, an alkoxy group having 1 to 5 carbon atoms and the group represented by the formulae:   R.sup.7 --Si(OR.sup.8).sub.3,       R.sup.7 --Si(OR.sup.8).sub.2 CH.sub.3,       R.sup.7 --Si(OR.sup.8)(CH.sub.3).sub.2     and     R.sup.7 --Y     (wherein R 7  represents a linear or branched alkylene group, or a linear or branched alkylene group having an ether or ester linkage, R 8  represents an alkyl group having 1 to 5 carbon atoms, and Y represents an aliphatic or alicyclic group having an epoxy group), provided that at least one of R 1  to R 6  is an alkoxy group and another at least one is epoxy group; l represents an integer of 1 to 20; m represents an integer of 0 to 4; and n represents an integer of 0 to 2),   in an amount of up to 30% by weight based on the weight of total solid in the colored coating composition.   
     
     
       14. The colored coating composition according to claim 1 further comprising a quaternary ammonium salt catalyst in an amount of 0.1 to 3% by weight based on the weight of total solid in the colored coating composition. 
     
     
       15. The colored coating composition according to claim 1 further comprising an organic tin compound in an amount of 0.2 to 6% by weight based on the weight of total solid in the colored coating composition. 
     
     
       16. The colored coating composition according to claim 1 further comprising crosslinked resin particles. 
     
     
       17. A method for forming a coated film, which comprises the steps of: (A) applying on an undercoated and/or intercoated substrate an colored coating composition comprising (a) 5 to 60% by weight of a polymer having a carboxyl group and a carboxylate group, which is obtained by reacting: (i) an acid anhydride group-containing polymer, obtained by copolymerizing (1) 15 to 40% by weight of an acid anhydride group-containing ethylenically unsaturated monomer, with   (2) 60 to 85% by weight of the other copolymerizable ethylenically unsaturated monomer; with     (ii) a hydroxyl group-containing compound having 1 to 12 carbon atoms; in an amount so that a molar ratio of the acid anhydride group to the hydroxyl group becomes 1/10 to 1/1;       (b) 5 to 60% by weight of a polymer having a hydroxyl group and an epoxy group, which is obtained by copolymerizing: (i) 5 to 70% by weight of a hydroxyl group-containing ethylenically unsaturated monomer represented by the formula: ##STR14##  (wherein R is a hydrogen atom or a methyl group, and X is an organic chain represented by the formula: ##STR15##  (wherein Y is a linear or branched alkylene group having 2 to 8 carbon atoms, m is an integer of 3 to 7 and q is an integer of 0 to 4) or an organic chain represented by the formula: ##STR16##  (wherein R is a hydrogen atom or a methyl group and n is an integer of 2 to 50)) and   (ii) 10 to 60% by weight of an epoxy group-containing ethylenically unsaturated monomer, and optionally   (iii) 0 to 85% by weight of the other copolymerizable ethylenically unsaturated monomer;     (c) 0.05 to 20% by weight of a pigment-dispersing agent; and   (d) 0.1 to 50% by weight of a pigment; (wherein, each amount formulated of the components (a) to (d) is based on the weight of total solid in the colored coating composition),   wherein, an acid total amount AR and a base total amount BR which are derived from said pigment-dispersing agent, and an acid total amount AP and a base total amount BP which are derived from said pigment, suffice the following relations:     AR>0.5 BP or BR>0.5 AP,     and     AR+AP>BR;     and       (B) curing the resulting coating by heating.   
     
     
       18. A coated product obtained by the method of claim 17.